The present invention relates to a printing mechanism for a printer of the serial printing type which is generally adapted for use in a desk-top calculator or the like.
A conventional serial printer prints sequentially. Therefore, in order to achieve a faster printing speed, the printing time and shifting time of a type drum must be shortened, and the type drum must also be rotated more rapidly. In a flying hammer-type printer, since the type drum is not stopped, the printing time is reduced. However, if the type drum is rotated at a higher frequency, unsatisfactory printing such as incomplete printing or irregular printing occurs. Since the type drum is typically shifted by one character pitch during one revolution of the drum, only one character can be printed upon each revolution of the drum, imposing a limit for a higher printing speed. In a printer of the stationary printing type, the printing quality is guaranteed if the drum is locked at a predetermined position. Although the type drum can be rotated at a high frequency a DC motor is, in most cases, adapted to drive the drum to reduce power consumption. Therefore, a clutch is required between the DC motor and the type drum. A printer of this type requires time for printing with the drum at a fixed position and shift time after printing for shifting the drum to the next character to be printed, also imposing a limit on a higher printing speed.